Background: Aerobic exercise can promote lipolytic potential, however the effect of aerobic exercise on lipids metabolism in individuals with different obesity levels remain unclear. Methods and results: Sprague Dawley rats were fed a high-fat diet to establish models of different obesity degrees, and they were subjected to 8 weeks of treadmill running. The weight and fat weight of the rats were collected, and blood lipids and leptin levels were measured. Subcutaneous fat samples were taken and stained with hematoxylin-eosin (HE) to observe the morphology of adipocytes. The expressions of adipocyte differentiation proteins were determined by Western blotting. The aerobic exercise group exhibited significant reductions in body weight, subcutaneous fat weight, and body fat percentage compared to the control group. Additionally, there were significant decreases in serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and leptin levels, as well as a decrease in adipocyte volume. Furthermore, high-density lipoprotein cholesterol (HDL-C) levels increased significantly along with the expression of adipocyte differentiation proteins Bone morphogenetic protein 4 (BMP4) and drosophila mothers against decapentaplegic protein 1 (SMAD1) proliferator activator receptor gamma (PPAR?), etc. Conclusions: Aerobic exercise significantly improved the body fat and lipid status of obese rats, and the improvement increased with increasing obesity. Exercise significantly reduced the volume of adipocytes, and the effect increased with increasing obesity. The effect of exercise on proteins involved in differentiation of subcutaneous adipocytes was not affected by obesity level.